If the dataset does not have image geolocation, it can be divided into subprojects manually:
One-flight Areal Project
Estimate the distance between the flight lines. It is recommended to divide the dataset in flight lines that have the smallest distance between them, so as to maximize the overlap between the subprojects.
Several-flight Aerial Project
Fly the different flights so that there is common area covered by as many flights as possible. Each flight can be one subproject.
Split the project into subprojects in such a way so that different subprojects share common images. This will ensure that there is overlap between the subprojects, which will facilitate merging.